The use of drug delivery devices for various types of drug therapy is becoming more common as the automated infusion of a drug may provide more reliable and more precise treatment to a patient.
Diabetes is a major health concern, as it can significantly impede on the freedom of action and lifestyle of persons afflicted with this disease. Typically, treatment of the more severe form of the condition, Type I (insulin-dependent) diabetes, requires one or more insulin injections per day, referred to as multiple daily injections. Insulin is required to control glucose or sugar in the blood, thereby preventing hyperglycemia which, if left uncorrected, can lead to ketosis. Additionally, improper administration of insulin therapy can result in hypoglycemic episodes, which can cause coma and death. Hyperglycemia in diabetics has been correlated with several long-term effects of diabetes, such as heart disease, atherosclerosis, blindness, stroke, hypertension, and kidney failure.
The value of frequent monitoring of blood glucose as a means to avoid or at least minimize the complications of Type I diabetes is well established. Patients with Type II (non-insulin-dependent) diabetes can also benefit from blood glucose monitoring in the control of their condition by way of diet and exercise. Thus, careful monitoring of blood glucose levels and the ability to accurately and conveniently infuse insulin into the body in a timely manner is a critical component in diabetes care and treatment.
In order to more effectively control diabetes in a manner that reduces the limitations imposed by this disease on the lifestyle of the affected person, various devices for facilitating blood glucose (BG) monitoring have been introduced. Typically, such devices, or meters, permit the patient to quickly, and with a minimal amount of physical discomfort, obtain a sample of their blood or interstitial fluid which is then analyzed by the meter. In most cases, the meter has a display screen which shows the BG reading for the patient. The patient may then dose themselves with the appropriate amount, or bolus, of insulin. For many diabetics, this results in having to receive multiple daily injections of insulin. In many cases, these injections are self-administered.
Due to the debilitating effects that abnormal BG levels can have on patients, i.e., hyperglycemia, persons experiencing certain symptoms of diabetes may not be in a situation where they can safely and accurately self-administer a bolus of insulin. Moreover, persons with active lifestyles find it extremely inconvenient and imposing to have to use multiple daily injections of insulin to control their blood sugar levels, as this may interfere or prohibit their ability to engage in certain activities. For others with diabetes, multiple daily injections may simply not be the most effective means for controlling their BG levels. Thus, to further improve both accuracy and convenience for the patient, insulin infusion pumps have been developed.
Insulin pumps are generally worn on the patient's body, either above or below their clothing. These relatively small, unobtrusive devices typically store a quantity of insulin in a replaceable cartridge and include a processing unit, a display screen, and input functions such as buttons or a keypad. Such pumps may include the ability to run multiple insulin delivery programs, such as basal and bolus programs, to eliminate the need for injections of insulin via needles and syringes, by providing medication via an infusion device that can be worn by the patient for an extended period of time, usually in the range of 1-3 days.
While the convenience of an insulin pump has helped to improve the lifestyle of diabetics and has lessened the impact of their disease on their normal activity, advances in insulin pumps are still needed. For example, in some diabetic patients who have dexterity problems, the patient cannot completely tighten the cartridge cap, resulting in potential loss of the pump air tight seal and loss of prime.
Therefore, it would be desirable for patients and caregivers to have a cartridge cap that locks into the cartridge chamber and that is ejected out of the chamber if it is not inserted properly.